Conventionally, an engine is generally cooled by coolant. It is also known to increase the heat load, in particular, on a cylinder head during the engine driving state.
In this regard, for example, Patent Document 1 discloses an engine cooling device that accelerates the warming up the engine cold state and is capable of suitably cooling the engine in the engine warm state.
Specifically, this cooling cooling device accelerates the warm up by causing the coolant to flow through the cylinder head and the cylinder block in this order without causing the coolant to flow through a radiator in the engine cold state. That is, the engine cooling device accelerates the warming up in the engine cold state in such a manner that utilizes the high heat load on the cylinder head.
Further, in the engine warm state, this engine cooling device causes the coolant to flow through the cylinder head (or the radiator and the cylinder head in this order if necessary) in the low load state, and causes the coolant to flow through the radiator, the cylinder head, and the cylinder block in this order in the high load state. Therefore, the engine cooling device is supposed to suitably cool the engine. That is, this engine cooling device preferentially cools the cylinder head on which the high heat load is imposed, and is then supposed to suitably ensure the cooling in the engine warm state.